I have Windows 10, but it should be the same I think. When I click on "attach files", it takes me right to the last directory I had open when I was logged on at Bob's. But let's say I didn't have an open directory the last time I was on Bob's, in a line above, near the top, you'll see where you're at right now. If you're in the C:/ directory, find the directory with the pictures you want to download, click on the picture, it uploads to Bob's. You then have to choose what size picture you want to display. Make your choice and you're all done uploading the picture.
When you do this, before you leave Bob's, be sure your cursor is at the Start of a new line.